Abstract:

Our Universe should be filled with a stochastic gravitational-wave background due to several traditional astrophysical sources and possibly some early-Universe sources. I will review some of these sources and then discuss work on an array of techniques to seek/constrain the gravitational-wave background, including measurement of small- and large-scale CMB temperature/polarization fluctuations, weak lensing, pulsar-timing measurements, stellar astrometry, and circular polarization of the CMB.